SnowLoadCheck

Shelby County, IL Roof Snow Load - 20 psf

How much snow is too much for a roof in Shelby County, IL?

Moderate
20 psf

20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Shelby County to carry. 14 psf is what the ground-load formula alone gives; Shelby County's 20 psf low-slope minimum (§7.3.4) beats it, so that figure is the one that governs on flat and low-pitch roofs.

Picture it, not just weigh it: 44 in. if it's fresh powder, 16 in. once it settles, or a mere 4 in. if it's ice. Modern-code homes carry a load like this without issue; an older addition, a carport, or any flat-roofed section is where it is worth checking first.

Already snow on the roof in Shelby County?

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Shelby County at a glance

How Shelby County compares

20 psf ranks #953 of 2,758 US counties with a mapped snow load (top 35%) - and #52 of 102 in Illinois. That's 0.7 psf above Illinois's own county-average design load of 19.3 psf.

Population 20,542 (FIPS 17173), roughly 39.3849°N 88.7989°W. The 20 psf ground snow load ASCE 7-22 maps here becomes 20 psf once the code's own design factors are applied.

Typical snowfall in Shelby County, IL

NOAA's 30-year normal for Shelby County: 16.2 in. of snow a year, from the BEECHER CITY, IL US station. (fresh vs. packed vs. ice explains why.)

What this Shelby County figure assumes

This is a county-level reference figure for a typical heated home built to Risk Category II (ordinary residential), on a partially exposed lot - the assumptions ASCE 7-22 itself treats as the default case. A steeper roof, a fully exposed hilltop lot, an unheated structure, or a higher risk category all change the actual number.

Shelby County's permit office wants an address-specific figure, not this county average - the ASCE 7 Hazard Tool is free, takes under a minute, and outputs a PDF most reviewers accept. Details: the calculation guide.